1. Field of the Invention
The present invention relates to a method of and an apparatus for predicting an image as a visible image which corresponds to a final image produced from image data that have been processed as desired.
2. Description of the Related Art
In recent years, there have widely been used printing systems for reading an image from an original document such as a photograph, a painting, or the like or processing image data supplied from an image input device and producing a printed material using a film original plate or a press plate.
Such a printed material is produced according to a number of processing steps. More specifically, color separation films of Y, M, C, K are produced on the basis of image data supplied from an image input device, and presensitized plates are exposed through each of the color separation films. Then, the presensitized plates are developed, and are set on a printing press to produce a color printed material. The quality of the printed material which is finally produced depends on various printing conditions (output conditions) including the paper, inks, and water used, the type of the printing press, and the screen ruling and dot configuration which are employed for the formation of dot-matrix images. In producing a printed image based on the above a number of processing steps and conditions, it is important to produce a predicted image in advance by outputting processed image data on a CRT, a printer, or the like, determine whether the predicted image is acceptable or not, and correct the converting or printing conditions if necessary.
The predicted image is required to have the equivalent image characteristics to those of a printed image by calorimetrically matching the individual colors of the pixels of the predicted image with those of the printed image, establishing formulas for matching output conditions such as optical characteristics depending upon the output method and resolution of output devices used, and the properties of a support layer for the printed image such as optical scattering, surface reflections, etc., and converting the image data supplied from the image input device according to the established formulas.
However, it is highly difficult to match in all the output conditions. Determining the image data of a predicted image according to the formulas which employ physical parameters related to a number of printed images is not practical as the processing operation is considerably time-consuming.